As a time code signal used for transmitting an image signal, LTC (Linear Time Code) signal subjected to a Biphasemark modulation and recorded in an audio frequency band can be mentioned. The time code signal is transmitted in a synchronous state with respect to the image signal.
The advancement in an image technology in recent years has realized a format conversion of the image signal. In general, when the format conversion is executed, the number of frames per second is increased or decreased. More specifically, the format conversion processing results in increasing or decreasing the number of image data (hereinafter, referred to as frame image data) per second constituting the respective frames in the image signal. Therefore, at least one frame image data of the respective frame image data constituting the image signal prior to the conversion is consequently eliminated or written in an overlapping state in the converted image signal.
When the format conversion is executed to the image signal, the image signal is inversely converted into a format prior to the conversion as circumstances demand. Hereinafter, the initial format conversion is called a primary conversion, and the format conversion for inverting the primary-converted image signal into the original image signal is called a secondary conversion.
In order to accurately secondary-convert the primary-converted image signal into the original image signal, it becomes necessary that the respective frames in the primary-converted image signal and the respective frames in the secondary-converted image signal accurately correspond to each other. In order to make them accurately correspond to each other, it is important to accurately grasp a frame position where any change is generated in the image data in the primary-converted image signal at the time of executing the secondary conversion (inverse conversion).
However, a conventional technology has neither established any configuration where a relationship between the frame position and the time code signal can be accurately grasped nor proposed any effective method in the time code signal corresponding to the primary-converted image signal.
Therefore, a main object of the present invention is to accurately grasp the relationship between the frame position and the time code signal in the image signal, which is subjected to the time of the primary conversion, to thereby accurately execute the format secondary conversion to the image signal.